The present application claims priority to Japanese Applications Nos. P2000-107066 filed Apr. 7, 2000, and P2000-396178 filed Dec. 26, 2000, which applications are incorporated herein by reference to the extent permitted by law.
The present invention relates to a power supply apparatus, which is suitably applicable to a power supply apparatus to reduce consumed power, for example, when a television set is in a waiting state.
In a television set, when the main switch is switched to its xe2x80x9conxe2x80x9d position after an AC plug is inserted into a commercial power supply, a commercial voltage is supplied from the AC plug to the main body which operates the television set""s intrinsic functions. The main body inside the television set operates based on the commercial voltage supplied from the AC plug, and is arranged to execute various kinds of process such as displaying an image onto, for example, a cathode ray tube display (CRT) or the like.
In addition, in the television set, to provide for remote operations from a remote controller, a subswitch is arranged to supply the commercial voltage to the main body inside the television set. In this case, the television set can be made to remain in a waiting state until it receives light form control signals overlapped onto the infrared ray from the remote controller.
In its waiting state, the television set is supplied the waiting power supply portion as well as the main power supply switch with the commercial voltage supplied by inserting the AC plug into a commercial power supply. The waiting power supply portion draws down as well as converts the voltage level of the commercial voltage supplied from the AC plug into a direct current voltage and supplies this to the light-receiving portion.
In addition, the main power supply switch remains in an off-duty state until a control signal is supplied from the light-receiving portion, and does not supply the commercial voltage supplied from the AC plug to a main body inside the television set.
The light-receiving portion receives light of control signals carried by the infrared rays from the remote controller to extract the control signals by photoelectric conversion so as to output these to the main power supply switch.
This serves to operate the main power supply switch so that the commercial voltage is supplied to the main body. Accordingly, the television set switches from the waiting operation state to the state where the main power supply is involved.
Thus, when the television set is in a waiting operation state, only the waiting power supply portion is arranged to consume the electric power, and thereby the television set in its entirety is arranged to plan energy saving.
Incidentally, in the waiting power supply portion with such a configuration, currents are caused to flow intermittently toward the primary side of the power supply transformer provided in its interior so that the power supply transformer is excited intermittently, and draws down as well as converts the voltage level of the commercial voltage via the secondary side of the power supply transformer into a direct current voltage and supplies this to the light-receiving portion.
In this case, compared with the case where the power supply transformer is always excited, it is excited intermittently to lessen the consumed energy of the waiting power supply portion, resulting in the waiting power supply portion""s consumed electric power being reduced, and this serves to make it possible to plan further energy saving for the television set in its entirety.
However, in a conventional waiting power supply portion, the main portion of the circuit for exiting the power supply transformer is provided on a primary side, and the current value inside the primary side will be increased so that it becomes necessary to make large the capacitor""s capacitance to store the currents inside the primary side circuit. That is, the waiting power supply portion was still insufficient for energy saving.
In addition, the waiting power supply portion in this case has a capacitor""s capacitance storing the currents to be supplied to the circuit at a primary side of the power supply transformer being large gives rise to a problem that a long time will be spent to store the currents into the capacitor.
In view of the foregoing an object of this invention is to provide a power supply apparatus which can save energy efficiently.
The foregoing object and other objects of the invention have been achieved by the provision of a power supply apparatus comprising: a power supply transformer; an excitation circuit, which is provided on a primary side of the power supply transformer to excite the power supply transformer with a predetermined alternating current power supply; and a control circuit, which is provided in a secondary side of the power supply transformer to start operation with the power supply transformer having entered an excited state and to intermittently operate the excitation circuit so as to make it possible to plan energy saving further efficiently.
The nature, principle and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings in which like parts are designated by like reference numerals or characters.